The question is not if the guard is helping, I think that everybody can make a conclusion that it helps but it has wind drag and that may be the problem. Mine is not hard enough so I can conclude that ONLY real 2mm carbon can help, I cannot carry Phantom woth mine since it bends so this one is no go for me. And I dont see it being so mich wind drag, I mean whole landing gear and gimbal+camera make drag so I just dont see how few of you could even notice that this small addition to the landing gear can make it unstable, battery eater etc.
Here is one real carbon for great price:
Carbon Fiber Gimbal Camera Landing Guard Protect Boards For DJI Phantom 3 RC BA